Accurate and precise quantification of atmospheric nitrate in streams draining land of various uses by using triple oxygen isotopes as tracers

Abstract

Land use in a catchment area has significant impacts on nitrate eluted from the catchment, including atmospheric nitrate deposited onto the catchment area and remineralized nitrate produced within the catchment area. In this study, we determined the spatial distribution and seasonal variation of stable isotopic compositions of nitrate for more than 30 streams within the same watershed, the Lake Biwa watershed in Japan, in order to use O-17 excess of nitrate as an additional tracer to quantify the mole fraction of atmospheric nitrate accurately and precisely.